1. Field of the Invention
The present invention relates to a method of testing a liquid developer, a liquid developer selected based on the testing method, and an image forming method and an apparatus, such as a photocopier, a facsimile machine, a printer, and the like using the selected liquid developer. The liquid developer includes improved characteristics, such as a decreased background soiling and an increased image density.
2. Discussion of the Background
As one electrophotographic image forming method, a liquid developing method is known, in which liquid developer is supplied to a narrow gap between a photoconductive member (electrostatic latent image bearer) and a liquid developer bearer, such as a developing roller or a developing belt. Thereby, solid toner particles in the liquid developer move toward and adhere onto a latent image carried on the photoconductive member to form a toner image. Such a developing method is referred to as "a narrow gap developing method." In general, an electrophotographic liquid image forming method providing a narrow gap developing method achieves a quality sharp image.
Japanese Laid-open Patent Publication No. 99157/1975 describes an electrophotographic liquid image forming method in which a dielectric release liquid is first applied to a latent electrostatic image on a charge-carrying surface. The latent electrostatic image is then developed with a dielectric cohesive ink by a developing roller or a developing belt coated with the same or a different dielectric release liquid. The developing roller and the developing belt are arranged apart from the charge-carrying surface by a narrow gap.
Japanese Laid-open Patent Publication No. 209922/1995 describes a liquid image forming method using a narrow gap developing method. A pre-wetting liquid is first applied to an electrostatic latent image on a photoconductive member. The latent image is developed with a liquid developer by a developing belt, which is arranged apart from the photoconductive member by a narrow gap.
The above dielectric release and pre-wetting, liquid methods make toner particles in the liquid developer not adhere to a non-image portion of the latent image on the charge carrying surface or the photoconductive member surface, and thereby background soiling on a recording medium is decreased. In addition, a replenishment and application mechanism for the liquid is required to supply the dielectric release or pre-wetting liquid. Accordingly, the production cost is increased for an image forming apparatus using such a dielectric release liquid or pre-wetting liquid. Further, the operating cost of the image forming, apparatus is increased due to the dielectric release liquid or pre-wetting, liquid.